Re: [nsp] Filtering OSPF

From: Jon.Maiman@inrange.com
Date: Tue Mar 19 2002 - 14:56:04 EST


Shawn,

        Since OSPF is a link state protocol, you can't filter individual
routes. All of the routers must have a consistent LSA database. You
do have a couple of other options though, depending on your requirements:

1) If your OSPF Areas are only single-homed (i.e. hub and spoke) with a
single ingress/egress router, you can use an OSPF Stubby or Totally Stubby
Area.

2) If your OSPF Areas are multi-homed, you can summarize routes at Area
Border Routers. This will reduce the number of routes propagated to
other areas. Finally, if you are re-distributing routes from another
routing protocol, you can also do summarization at Autonomous System
Boundary Routers.

You might want to take a look at Cisco's OSPF Design Guide for more
details, http://www.cisco.com/warp/public/104/1.html.

Hope this helps....

 --Jon

"Gyorfy, Shawn" <sgyorfy@elinkny.com>
03/19/02 02:57 PM

 
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        Subject: [nsp] Filtering OSPF

Question:
Using Cisco equipment:

I have 4 OSPF Areas with X number of routers per area. As of right now
the
access routers are getting a full routing table from the border router as
per their appropriate area. I would like to limit their routing table so
they only get the default route. I am looking at distribution list, am I
hot on this one or still cold?

shawn



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